Sole for a shoe, boot or sandal

ABSTRACT

An insert  2, 3,  for a sole of a shoe, boot or sandal is provided to give a cushioning effect. The sole  1  comprises a first integrally formed member which forms part of the sole  1  and which has a sole tread pattern on the first surface thereof, and a second integrally formed member  2, 3,  in the form of an insert received in a cavity of the first member so that it is received in the cavity above a mounting surface  5,  the mounting surface  5  being formed on a surface opposed to the surface having the sole tread pattern.  
     There are a plurality of projections  6  projecting away from the mounting surface  5.  The inserts  2,3,  have parts whose thickness in a direction normal to the mounting surface is lower than the thickness of other parts of the respective insert in a direction parallel to the mounting surface  5.  The projection  6  engage the parts of the inserts  10  having lower thickness, at least the insert being formed of a resilient material to increase the springiness of the sole, the projections and the reduced thickness portions each extending in two directions parallel to the mounting surface for a distance lower than the corresponding dimensions of the mounting surface.

BACKGROUND TO THE INVENTION

The present invention relates to a shoe sole and to an insert for a shoe sole.

The general term ‘shoe’ used herein includes a boot or sandal, unless it is indicated otherwise.

Any discussion of the prior art throughout the specification should in no way be considered as an admission of that such prior art is widely known or forms part of common general knowledge in the field.

It is well-known that a sole of a shoe must be relatively rigid, so that the shoe can be worn outdoors without being damaged. However, the rigidity required for normal functioning of a sole of a shoe can result in discomfort to the wearer. An insert can be put in the sole, to provide cushioning and comfort. The nature of the insert will depend on the use of the shoe in which it is intended to be inserted.

Cushioning has been provided in the past by trapped air pockets formed in the sole, but such air pockets are vulnerable to puncture.

It is also desired to provide an insert for cushioning which is simple to manufacture and does not excessively increase the weight of the sole.

It is an object of the present invention to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative.

THE INVENTION

The present invention provides a sole for shoe, boot or sandal, having a first integrally formed member which forms part of the sole and which has a sole tread pattern on a first surface thereof, and a second integrally formed member in the form of an insert received in a cavity of the first member so that it is received in the cavity above a mounting, surface the mounting surface being formed on a surface opposed to the surface having the sole tread pattern, there being a plurality of projections projecting away from the mounting surface, the insert having parts whose thickness in a direction normal to the mounting surface is lower than the thickness of other parts of the insert in the direction normal to the mounting surface, the projections engaging parts of the insert having lower thickness, at least the insert being formed of a resilient material to increase the springiness of the sole, the projections and the reduced thickness portions each extending in two directions parallel to the mounting surface for a distance lower than the corresponding dimensions of the mounting surface.

The sole of the invention has the advantage that the cushioning effect is provided by components which are formed on surfaces other than the surface of the sole comprising the tread pattern. This means that the tread pattern can be any pattern required, for example to give good grip, without reducing or affecting the cushioning function.

The sole of the present invention comprises two members, each of which is integrally formed. These members are relatively easy to manufacture and simple to assemble. Where inserts are formed by laminating a number of components adjacent to one another, there is a danger of wear and dislocation making the inserts unusable after a very short period.

The sole of the present invention has a further advantage that, whereas a number of solutions in the prior art have been proposed which use bars or ribs, the present invention uses projections and reduced thickness portions each of which is relatively small compared to the mounting surface. Each projection or reduced thickness portion may therefore have an enhanced springiness compared to a bar. By providing a relatively large number of such projections and reduced thickness portions, each projection and reduced thickness portion only bears a relatively small proportion of the total weight, allowing the weight to be spread out in a comfortable manner and preventing overload of any particular part of the sole, thereby reducing the amount of damage.

The projections are suitably formed of a resilient material. They preferably have a maximum dimension parallel to the mounting surface in the range 3-8 mm. They may be circular or elliptical in cross section in the plane parallel to the mounting surface. Similarly, the reduced thickness portions may be formed of resilient material. They may have a maximum dimension in the plane parallel to the mounting surface in the range 5-12 mm. They may be circular or elliptical when seen in the plane parallel to the mounting surface.

It is preferable that at least part of the insert is displaceable with respect to the projections in a direction generally parallel to the mounting surface, the reduced thickness portions of this part of the insert having an elliptical shape when seen in the plane parallel to the mounting surface. This arrangement allows the components of the sole to move in a natural manner when the sole is flexed during walking. By providing an elliptical reduced thickness portions, the projections are always in contact with at least part of the reduced thickness portion, so that the springiness is not loss during flexing.

Suitably, each projection engages a respective reduced thickness portion over at least 50% of its area when seen a plane parallel to the mounting plane.

Suitably, the insert is mounted in a heel portion of the sole. In this case, there are preferably between 5 and 20 projections and corresponding reduced thickness portions, more preferably between 8 and 16 projections and corresponding reduced thickness portions.

The insert may be mounted in a forepart of the sole. In this case, there are preferably between 20 and 60 projections and corresponding reduced thickness portion, most preferably between 30 and 50 projections and reduced thickness portion.

The sole may comprise an insert in the heel and in the forepart.

Preferably, the insert of the invention is made of polyvinyl chloride (PVC). Alternatively, the insert is made of ethylene-vinyl acetate copolymer (EVA) or polyurethane. The Shore A hardness of the material of the insert is preferably not more than about 65 and is preferably not less than about 40 or 35. In a preferred embodiment, the Shore A hardness of the material of the insert is approximately 50±5 through it could be say as low as 40, softer inserts being preferred for children. The specific gravity of the material from which the insert is made is preferably not more than about 1.15 g/cm³ and is preferably not less than about 0.4 g/cm³. The specific gravity of the material is preferably within the range 0.7 to 0.75 g/cm³.

The sole and/or the insert may comprise a lightening structure, such as holes.

Locating structures may be provided for restricting relative movement of the sole with respect to the insert in the plane of the sole. For example, at least one of the sole or insert may comprise a projection for engaging a recess formed in the other of the sole or insert.

The present invention will be further described by way of example and with reference to the accompanying drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a sketch isometric view of a sole in which an insert may be placed, in accordance with the present invention.

FIG. 2 shows a sketch isometric view of a design of insert for insertion into the forepart of the sole of FIG. 1

FIG. 3 shows a sketch isometric view of a insert for insertion into the heel portion of the sole of FIG. 1.

FIG. 4 shows a cross sectional view along line IV-IV of FIG. 1.

FIG. 5 shows a plan view of a second embodiment of a sole according to the present invention having inserts in the sole and forepart thereof.

DESCRIPTION OF PREFERRED EMBODIMENT

FIG. 1 shows a sole 1 into which a heel insert 2 and forepart insert 3 as shown in FIGS. 2 and 3 are inserted as shown in FIG. 4. The inserts 2 and 3 are received in cavities formed in a lower sole 4. This lower sole 4 has two mounting surfaces 5 which can be seen in FIG. 2. A plurality of projections in the form of circular section pillars 6 are formed projecting upwardly from the mounting surfaces 5. It can be seen that the projections 6 are formed into a regular pattern to provide evenly spread support across the area of each insert. It can be seen that the pattern of the projections 6 is independent of the respective sole tread pattern 7 and 8.

Each insert 2, 3 comprises areas 9 of higher thickness in a direction normal to the respective mounting surface 5 and areas 10 of reduced thickness in a direction normal to the respective mounting surface 5.

The projections 6 engage respective areas of reduced thickness of the respective insert. Each insert 2, 3 is only supported on the respective mounting surface 5 by contact between the reduced thickness areas and the projection 6. The insert is formed of a resilient material, for example a blown PVC or a soft, plasticised PVC. It may be EVA or polyurethane. The material of the insert 2 should have a shore A hardness of no more than about 65 and no less than about 35, suitably about 50.

The projections 6 are substantially circular in cross section seen in the plane parallel to the mounting surface 5. The reduced thickness areas 10 of the inserts 2,3 are of circular or elliptical shape, seen the plane parallel to the mounting surface 5. The projections 6 engage substantially in the centre of the respective elliptical or circular reduced thickness area 10. The projections 6 suitably have a diameter in the range 3-8 mm, preferably around 5 mm and the reduced thickness areas 10 suitably have a diameter or major axis dimension in the range 5-12 mm, preferably about 10 mm.

A large number of projections and corresponding reduced thickness areas 10 are provided, in a closely spaced pattern, to ensure an evenly spread, high level of support. For example, the heel insert is shown as having eleven areas of reduced thickness 10. Rows 3 of weight reducing holes may be formed in the insert suitably in the spaces between areas of reduced thickness.

The heel insert 2 is designed as an integral structure which can be formed in a single injection moulding operation. The forepart insert 3 is shown as a two part structure comprising a first forepart insert 11 and second forepart insert 12. The first forepart insert 21 engages the second forepart insert 12 by way of interdigitating projections 14, and 15. The interdigitating projections form a kind a hinge, but there is no pin, so that the first forepart insert 11 can move longitudinally with respect of the second forepart insert 12. The movement generally occurs at the position of the interdigitating projections and the areas of reduced thickness 16 in this area are formed of an elliptical shape rather than a circular shape, so that if the respective insert part moves a few millimetres during flexing of the foot with respect to the projections 6, the projections 6 will still engage substantially in the centre of the respective reduced thickness area 16.

In the same way as the first embodiment, the specific gravity of the insert can vary but it is preferably in the range of 0.7-0.75 gcm³ The specific gravity of the lower sole 2 is preferably in the range 1.12 to 1.5 gcm³. Between the heel insert 2 and the forepart insert 3, the top of the sole can be flat or it can be provided with cavities for example a number of square cavities as shown, divided by relatively narrow walls.

In order to locate the insert 2,3, within the sole 1, each insert has notches 17 formed in suitable positions which, when the insert 2 or 3 is placed in the sole, engage with projections 18 formed in the sole. The projections 18 and indentations 17 will be dimensioned so that they fit relatively closely.

FIG. 5 is a sketch plan view of a second embodiment of sole according to the present invention. It comprises a sole 19 with a heel insert 20 and a fore part insert 21. Many features of the sole 19, heel insert 20 and fore part insert 21 are the same as described for the first embodiment. However, each of the inserts 20 and 21 comprises a plurality of lightening holes 22, 23 to reduce the overall mass of the sole when assembled.

Unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise”, “comprising”, and the like are to be construed in an inclusive as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to”.

The present invention has been described above purely by way of example, and modifications can be made within the spirit of the invention. The invention also consists in any individual features described or implicit herein or shown or implicit in the drawings or any combination of any such features or any generalisation of such features or combination. 

1. A sole for shoe, boot or sandal, having a first integrally formed member which forms part of the sole and which has a sole tread pattern on a first surface thereof, and a second integrally formed member in the form of an insert received in a cavity of the first member so that it is received in the cavity above a mounting surface, the mounting surface being formed on a surface opposed to the surface having the sole tread pattern, there being a plurality of projections projecting away from the mounting surface, the insert having parts whose thickness in a direction normal to the mounting surface is lower than the thickness of other parts of the insert in the direction normal to the mounting surface, the projections engaging parts of the insert having lower thickness, at least the insert being formed of a resilient material to increase the springiness of the sole, the projections and the reduced thickness portions each extending in two directions parallel to the mounting surface for a distance lower than the corresponding dimensions of the mounting surface.
 2. The sole of claim 1, wherein the projections are formed of a resilient material.
 3. The sole of claim 1, wherein the projections have a maximum dimension parallel to the mounting surface in the range 3-8 mm.
 4. The sole of claim 1, wherein the projections are generally circular in cross section in a plane parallel to the mounting surface.
 5. The sole of claim 1, wherein the reduced thickness portions of the insert have a maximum dimension in the plane parallel to the mounting surface in the range 5-12 mm.
 6. The sole of claim 1, wherein the reduced thickness portions of the insert are generally circular or elliptical when seen in a plane parallel to mounting surface.
 7. The sole of claim 1, wherein at least part of the insert is displaceable with respect to the projections in a direction generally parallel to the mounting surface, the reduced thickness portions of this part of the insert having an elliptical shape when seen in a plane parallel to the mounting surface.
 8. The sole of any of claim 1, wherein each projection engages a respective reduced thickness portion over at least 50% of its area seen in the plane parallel to the mounting plane.
 9. The sole of claim 1, wherein the insert is in the fore part of the sole.
 10. The sole the sole of claim 1, wherein the insert is in the heel of the sole.
 11. The sole of claim 1, wherein the Shore hardness of the insert is not more than
 65. 12. The sole of claim 12, wherein the Shore hardness of the material of the insert is not less than
 40. 13. The sole of claim 1, wherein the specific gravity of the insert is not more than 1.15 g/cm³.
 14. The sole of claim 14, wherein the specific gravity of the material from which the insert is made is not less than 0.4 g/cm³.
 15. A shoe, boot or sandal comprising a sole according to claim
 1. 